Rhymney 062T models

[Penrhos1920]

At the moment if you want to model the Rhymney in either 4mm or 7mm the only 'easy' option is a kit for the AR class. Unfortunately for me this kit is not very helpful as the AR class were built in 1921; after when I'm modelling. Some people might have seen that I was building a Rhymney A class using 3D printing as the start point. Unfortunately the 3D printing quality was not good enough and I gave up after countless hours of sanding and filling pieces.

Well now the project has grown and 3D printing has improved. Below are CAD drawings of classes M, R, A, A1 and A1 built as A. The project will also include the P and P1 class; but not the AP class as these are also too late. However, I might be drawing a GWR standard boiler so that so of the rebuilds can be modelled. I particularly like the A1 with a GWR boiler. As an aside, I also fancy PTR nos. 20 & 21 with a GWR boiler.

Having been starring at these drawings for ages I now can't see any issues. But I know I've missed the bleeding obvious! So please point it out before I get them printed and then bang my head against the brick wall.

RR M model.jpg

RR R model.jpg

RR A model.jpg

[Penrhos1920]

RR A1 model.jpg

RR A1 exA model.jpg

I've also drawn a chassis that can be printed in a stronger, slightly flexible material. The detailing parts will be printed in the high detail material and glued on. All axles run in brass bearings glued into the holes except the middle axle which floats.

RR A1A chassis.jpg

Fortunately I've been able to scan the builders drawings and GWR modifications that are available at York. Lots of drawings ( over 120 just for the A1) so most things should be ok, but I only have a few drawings for the M class. Let me know your thoughts please.

[Penrhos1920]

Noel,
Yes there is a radial truck, but I've modelled it as a pony truck (the green separate part) so that it is freer is move sideways. It needs side control and load bearing springs. The centre driver is floating as opposed to fixed like the other axles. It also needs some springing, I'm thinking that it can be done rather like Bachmann do their 060T where there is a sprung shoe holding the axle down.

The chassis is designed for OO & O. I'm not sure why you thought it was for P4 as I was careful not to mention gauge. In OO the frames are 2mm thick, except around the gearbox area where they are only 1.5mm thick, and 13mm over faces. They are specifically designed for the Highlevel RoadRunner+ gearbox which gives a good choice of ratios. In O gauge there is no need to reduce the frame width around the gearbox.

RR A1A chassis2.jpg

[Penrhos1920]

Many thanks Noel, I appreciate your help.

I must confess I've not thought enough about the chassis. My experience of P4 folk is that they generally prefer either an etched brass chassis or to build their own using their preferred type of suspension; rather than work from an OO chassis. Being 3D printed and in a different material the chassis would be ordered separately.

If there is enough interest then I'll make them available to others. That's part of my thinking about showing them here; so that anyone in the Circle can see them and express an interest.

[Newport_rod]

Richard,

I had wondered what had become of the A class but glad to see that you’ve revived the idea. I’m yet to be convinced about the suitability of 3d printing for locos because of the surface quality issues you allude to but I’m sure the technology is very close to being acceptable for this application. Certainly the quality of Modelu products bodes well.

Rather like Noel I don’t know enough of the Rhymney locos do be able to make definitive comment about their accuracy.

On chassis design though, I haven’t yet tried any 3d printed chassis so can’t comment on its suitability as a material. One immediate suggestion, however, would be to taper the material away at the frame cut-outs to reduce the visible excess thickness. I do like the idea of the keeper-plates allowing the driving wheel sets to be removable. Following up on your thought to make the centre axle floating could this be achieved by leaving a 6mm wide rebate to accept Alan Gibson hornblocks? And from there perhaps produce a variant for P4 (and for that matter EM) with rebates for each driven axle.

Alternatively with the GWR 56xx having been based on, and sharing the wheelbase of, the RR M and R is there an opportunity to utilise or adapt the High Level chassis at least for the 4’7½” diameter wheel locos? Perhaps High Level may be induced to provide a 5’ diameter version for the P.

But my biggest request would be to produce B&M variants for both the 4’7” and 5’ locos. And I’d be happy to help in that direction.

Rod

[Newport_rod]

Richard

I only have a limited selection of photos of RR 0-6-2s but all I've found is a couple of differences (which may just be variations within the class)

R class - should the steps at the front of the tank only have a single step (as No 3) or two steps but without the curve towards the bottom of the step (as 17)? There appears to be beading in the splasher to the leading wheel.

M class - should the handrail on the tank be on the curve rather than the front face? I see that you've selected the later variant with the leading drivers leaf springs over the wheel rather than under.

Hope this helps
Rod

[Penrhos1920]

Richard,

I had wondered what had become of the A class but glad to see that you’ve revived the idea. I’m yet to be convinced about the suitability of 3d printing for locos because of the surface quality issues you allude to but I’m sure the technology is very close to being acceptable for this application. Certainly the quality of Modelu products bodes well.

Modelu and many other 3d printing uses have one big advantage over locomotives and coaches, they do not have large flat expanses finished in a high gloss paint. 3d printing hasn't yet quite got to the position where one layer is exactly on top of the layer below yielding a smooth surface. But it is close and getting closer.

On chassis design though, I haven’t yet tried any 3d printed chassis so can’t comment on its suitability as a material. One immediate suggestion, however, would be to taper the material away at the frame cut-outs to reduce the visible excess thickness. I do like the idea of the keeper-plates allowing the driving wheel sets to be removable. Following up on your thought to make the centre axle floating could this be achieved by leaving a 6mm wide rebate to accept Alan Gibson hornblocks? And from there perhaps produce a variant for P4 (and for that matter EM) with rebates for each driven axle.

Alternatively with the GWR 56xx having been based on, and sharing the wheelbase of, the RR M and R is there an opportunity to utilise or adapt the High Level chassis at least for the 4’7½” diameter wheel locos? Perhaps High Level may be induced to provide a 5’ diameter version for the P.

I have tried adapting a High Level chassis and made a total mess of it as it needs to chopped down above the cylinders. I doubt many P4 /EM modellers would want anything but an etch chassis. For the RR A, M & R I think the Comet chassis is probably a better starting point for P4 and EM modellers. I've also looked at the Bachmann 56xx chassis, but it really needs access to a milling machine to reduce the width of the cast block that fills the tanks.

But my biggest request would be to produce B&M variants for both the 4’7” and 5’ locos. And I’d be happy to help in that direction.

Rod

That can be on the books. Reading the RCTS book it doesn't sound too difficult.